Semiconductor lasers are attractive for a wide variety of applications including telecommunications, computing systems, optical recording systems and optical interconnection of integrated circuits. Semiconductor lasers provide compact sources of coherent, monochromatic light which can be modulated at high bit rates to transmit large amounts of information.
Vertical-cavity surface emitting lasers are particularly promising for applications requiring low cost lasers. As contrasted with edge emitting lasers which emit light parallel to the semiconductor growth planes of their substrates, VCSELs emit light perpendicular to growth planes. A typical VCSEL comprises an active semiconductor region sandwiched between a pair of distributed Bragg reflectors. Upon injection of suitable current through the active region, laser light is transmitted perpendicular to the growth planes.
In a paper entitled "Vertical-Cavity Surface-Emitting Laser Diodes Fabricated by In Situ Dry Etching and Molecular Beam Epitaxial Regrowth" authored by Kent D. Choquette et al and published in IEEE Photonics Technology Letters, Vol.5, No. 3, pp. 284-287, a method was described for fabricating lasers having mesa-type structures.
Oxide-apertured VCSELs are fabricated by lateral oxidation of an AlGaAs layer in the current path that, when sized properly, constricts the current by a desired amount. Many references to this method are available such as one authored by D. L. Huffaker, L. A. Graham, H. Deng, and D. G. Deppe entitled "Sub-40 .mu.A Continuous-Wave Lasing in an Oxidized Vertical-Cavity Surface-Emitting Laser with Dielectric Mirrors", that appeared in IEEE Photonics Technology Letters, Vol. 8, No. 8, August 1996 and is incorporated herein by reference.
One problem with this and similar methods however, is that the rate of oxidation is variable and generally considered uncontrollable to a desired amount. In view of this, it will be apparent that methods for enhancing the manufacture of oxide-apertured VCSELs are highly desirable. We disclose herein such a method.